1. Field of the Invention
The present invention relates to flexible heaters, and more particularly to a novel flexible heater adapted to be insertably received in gloves and boots or other wearing apparel for the purpose of heating a specified area and which will readily flex during movement of the person wearing the heater so that conductive circuits will not be broken or disrupted.
2. Brief Description of the Prior Art
In the past, it has been the conventional practice to provide a variety of heaters which employ wires that are directly embedded in various portions of clothing so that the wearer of the clothing will receive the benefit of heat. This has been particularly useful in the aviation industry where wires have been run through flying clothing as well as flying boots wherein the principles of electrical resistive heating are used. However, problems and difficulties have been encountered when employing such clothing with wire conductive paths that stem largely from the fact that wires readily break when flexed so that body movements of the wearer tend to sever electrical conductive paths disrupting the circuits. In such instances, the use of the device as a heater is completely eliminated and rendered useless for its intended purpose.
Other problems and difficulties have been encountered when dealing with wires that stem largely from the fact that wires as a conductive path for electricity are generally thick since each individual wire is of circular cross-section having a definite diameter. Also, because of the propensity of wire to break when bent during body movements of the wearer, the wires cannot be placed close together since short-circuiting may occur at any time. Even when heavy insulative material is placed between the wire conductors, severing of the conductor will oftentimes cause the wire to engage with adjacent wires to cause the short circuit. It is relatively easy for a severed wire conductor to protrude through adjacent insulative material since the breakage of a wire leaves sharp edges that may cut or sever the insulation.
Furthermore, historically, wire conductors do not provide suitable strain relief during pulling or flexing body movements of the wearer so that the wires may readily be flexed to the point of breakage or, literally, the wire conductors are pulled from sockets, power source, switch connections or the like.
Therefore, a long standing need has existed to provide a novel heater that is composed of a unitary insulative and strip-conductive paths which are of unitary construction so that the heater may be readily slipped or introduced into wearing apparel such as boots or gloves. The flexible conductive circuits should be provided with a strain relief means so that normal body movements of the wearer will not fatigue the conductors nor cause inadvertent breakage thereof.